Add a way to remove menu bar icon

[dcaspi]

The menubar icon takes up space and is not necessarily useful, given the convenient shortcuts.

Most apps that have a menubar icon usually provide a way to hide it, and I think it could be useful here too.

Thank you :)

[astoilkov]

In the next version, there will be an option to hide the app from the dock. I'm wondering how this can be combined with hiding from the menu bar because hiding from both places makes it hard to determine if the app is running. We think about it when we plan for 0.10.

Thanks for the suggestion!